The invention relates to a ground freezing device with a freeze pipe, which is closed at one front side, and an inner pipe extending into the freeze pipe for supplying a cooling agent. The invention further relates to a method for freezing the ground with a freeze pipe and an inner pipe extending into the freeze pipe, wherein a refrigerant is guided into the freeze pipe via the inner pipe.
In civil and foundation engineering, measures must often be taken to seal or support the ground. During temporary jobs, it makes sense to artificially freeze the ground with liquid nitrogen as the coolant.
When freezing the ground, the cold is introduced via a freeze pipe with a dual pipe system. Liquid nitrogen passes downwardly through an inner pipe and into the freeze pipe, evaporates, and while rising in the annular space imparts its cooling energy to the surrounding soil. Extracting the heat cools and freezes the water in the surrounding soil.
After icing is complete, the freeze pipes as a rule remain in the soil. In some cases, however, this impedes the continued construction process, e.g., since whole section boring machines are unable to pass through the steel or copper pipes used as the freeze pipes. In these instances, it is thus necessary to remove the freeze pipes from the soil after icing.
However, pulling the freeze pipes proves problematical for several reasons. After icing is complete, the surrounding soil is still frozen for weeks. The tensile force that can be applied to the freeze pipes is limited by the material, and pulling the freeze pipe also generates a vacuum on its lower side, which exerts a force on the freeze pipe that counteracts the pulling.
Therefore, the object of the present invention is to indicate a ground freezing device and a corresponding method, which makes it easier to remove freeze pipes from the ground.